Systems and methods for operating an implantable medical device

ABSTRACT

A system and/or method to control operation of an implantable medical device in response to a monitored gravity vector.

CROSS REFERENCE TO RELATED APPLICATIONS

This Continuation application claims priority to U.S. application Ser.No. 16/978,275 filed Sep. 4, 2020, which claims priority under 35 U.S.C.§ 371 to International Application No. PCT/US20/043442, filed Jul. 24,2020, which claims the benefit of U.S. Provisional Patent ApplicationSer. No. 62/878,531, filed Jul. 25, 2019; all of which are incorporatedherein by reference.

BACKGROUND

Many patients benefit from therapy provided by an implantable medicaldevice. For example, a portion of the population suffers from variousforms of sleep disorder breathing (SDB). In some patients, externalbreathing therapy devices and/or mere surgical interventions may fail totreat the sleep disordered breathing behavior. With these and otherimplantable medical device therapy applications, operation of suchsystems can be improved with reference to sensed patient information.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram schematically illustrating a patient caresystem in accordance with principles of the present disclosure.

FIG. 2 is a block diagram schematically representing an implantablemedical device useful with the care system of FIG. 1 and in a partiallyassembled state.

FIG. 3 is a block diagram schematically representing the implantablemedical device of FIG. 2 in an assembled state and an implantable sensorin accordance with principles of the present disclosure assembled to theimplantable medical device.

FIG. 4 is a block diagram of portions of another patient care system inaccordance with principles of the present disclosure and including animplantable sensor carried within the housing of an implantable pulsegenerator assembly.

FIG. 5 is a block diagram schematically representing an example sensorlead useful with the patient care system of FIG. 1 and including astimulation electrode and an implantable sensor.

FIG. 6 is a block diagram schematically representing an example systemincluding an implantable pulse generator assembly and a separateimplantable sensor in accordance with principles of the presentdisclosure.

FIG. 7A schematically represents an axis orientation diagram of a threeaxis accelerometer useful as one non-limiting example of an implantablesensor of the present disclosure.

FIG. 7B is a block diagram schematically representing a sectional viewof an example IPG assembly carrying an implantable sensor implantedwithin a body in association with an axis orientation diagram.

FIG. 8 schematically represents positional information obtained for apatient in a lying down position in accordance with some embodiments ofthe present disclosure.

FIG. 9A is a block diagram schematically representing an example controlportion.

FIG. 9B is a diagram schematically representing at least some examplesdifferent modalities of the control portion of FIG. 9A.

FIG. 9C is a block diagram schematically representing an example userinterface.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings which form a part hereof, and in which is shown byway of illustration specific examples in which the disclosure may bepracticed. It is to be understood that other examples may be utilizedand structural or logical changes may be made without departing from thescope of the present disclosure. The following detailed description,therefore, is not to be taken in a limiting sense. It is to beunderstood that features of the various examples described herein may becombined, in part or whole, with each other, unless specifically notedotherwise.

At least some examples of the present disclosure are directed to systemsand devices for diagnosis, therapy and/or other care of medicalconditions. At least some examples may comprise implantable devicesand/or methods comprising use of implantable devices.

At least some examples of present disclosure are directed to systems andmethods for controlling at least one function or operation of animplantable medical device system, including an implantable medicaldevice implanted within a patient, based upon sensed posture informationof the patient. In some embodiments, one or more sensors implanted inthe patient are utilized to sense or detect the posture information ofthe patient. In some embodiments, the operations of the implantablemedical device system that are controlled in response to the sensedposture information relate to an operational mode of the implantablemedical device in delivering therapy to the patient. In someembodiments, the systems and methods of the present disclosureincorporate one or more algorithms that result in an action being takenin response to a determination that the patient is in a designatedposture or a determination that the probability the patient is in adesignated posture is above a threshold; in other embodiments, thesystem and methods of the present disclosure incorporate one or morealgorithms that result in an action being taken in response to adetermination that the patient is not in a designated posture or adetermination that the probability the patient is not in a designatedposture is above a threshold. In some embodiments, the operations of theimplantable medical device system that are controlled in response to thesensed posture information relate to determining or designating acurrent posture of the patient. In some embodiments, the operations ofthe implantable medical device system that are controlled in response tothe sensed posture information relate to determining or designating thata current posture of the patient is not a designated or particularposture. In some embodiments, the operations of the implantable medicaldevice system that are controlled in response to the sensed postureinformation relate to calibrating information signaled by one or moresensors. In some embodiments, the operations of the implantable medicaldevice system that are controlled in response to the sensed postureinformation relate to generating information or data for review by thepatient and/or caregiver.

In some examples, the systems and methods of the present disclosure areconfigured and used for sleep disordered breathing (SDB) therapy, suchas obstructive sleep apnea (OSA) therapy, which may comprisesmonitoring, diagnosis, and/or stimulation therapy. However, in otherexamples, the system is used for other types of therapy, including, butnot limited to, other types of neurostimulation or cardiac therapy. Insome embodiments, such other implementations include therapies, such asbut not limited to, central sleep apnea, complex sleep apnea, cardiacdisorders, pain management, seizures, deep brain stimulation, andrespiratory disorders.

One example of a patient therapy system 20 in accordance with principlesof the present disclosure is schematically represented in FIG. 1 . Thepatient therapy system 20 includes an implantable medical device (IMD)30, one or more implantable sensors 32, a posture module or handler 34,and an optional external device 36. Details on the various componentsare provided below. In general terms, the IMD 30 is configured forimplantation into a patient, and is configured to provide and/or assistin the performance of therapy to the patient. The implantable sensor 32can assume various forms, and is generally configured for implantationinto a patient and to at least sense a parameter indicative of a postureof the patient. The implantable sensor 32 can be carried by the IMD 30,can be connected to the IMD 30, or can be a standalone component notphysically connected to the IMD 30. The posture module 34 receivesinformation from the implantable sensor 32 and is programmed (or isconnected to a separate module that is programmed) to recognize oridentify or determine a current posture of the patient based, at leastin part, upon information from the implantable sensor 32. In someembodiments, the posture module 34 is programmed (or is connected to aseparate module that is programmed) to effect (or not effect) one ormore control routines or the like relating to operation of the system20. As described below, the posture module 34 can be incorporated by theIMD 30 (e.g., installed into a software application operated by the IMD30), or can reside, either partially or entirely, with other componentsof the system 20. Where provided, the external device 36 can wirelesslycommunicate with the IMD 30, and is operable to facilitate performanceof one or more operations as described below (e.g., the external device36 can be used to initially program the IMD 30, and the IMD 30 thenprocesses information (e.g., posture information) and delivers therapyindependent of the external device 36). In other embodiments, theexternal device 36 can be omitted (e.g., the IMD 30, the implantablesensor 32 and the posture module 34 perform one or more of theoperations described below without the need for an external device).

FIG. 2 is a block diagram schematically representing one example of anIMD 50 useful with the systems and methods of the present disclosure,for example as the IMD 30 of the system 20 of FIG. 1 . The IMD 50 caninclude an implantable pulse generator (IPG) assembly 52 and astimulation lead 54. The IPG assembly 52 can include a housing 60containing circuitry 62 and a power source 64 (e.g., battery), and aninterface block or header-connector 66 carried or formed by the housing60. The housing 60 is configured to render the IPG assembly 52appropriate for implantation into a human body, and can incorporatebiocompatible materials and hermetic seal(s). The circuitry 62 caninclude circuitry components and wiring apparent to one of ordinaryskill appropriate for generating desired stimulation signals (e.g.,converting energy provided by the power source 64 into a desiredstimulation signal), for example in the form of a stimulation engine. Insome embodiments, the circuitry 62 can include telemetry components forcommunication with external devices as is known in the art. For example,the circuitry 62 can include a transmitter that transforms electricalpower into a signal associated with transmitted data packets, a receiverthat transforms a signal into electrical power, a combinationtransmitter/receiver (or transceiver), an antenna, etc.

In some embodiments, the stimulation lead 54 includes a lead body 80with a distally located stimulation electrode 82. At an opposite end ofthe lead body 80, the stimulation lead 54 includes a proximally locatedplug-in connector 84 which is configured to be removably connectable tothe interface block 66 (e.g., the interface block 66 can optionallyinclude or provide a stimulation port sized and shaped to receive theplug-in connector 84 as is known in the art).

In general terms, the stimulation electrode 82 can optionally be a cuffelectrode, and can include some non-conductive structures biased to (orotherwise configurable to) releasable secure the stimulation electrode82 about a target nerve. Other formats are also acceptable. Moreover,the stimulation electrode 82 can include an array of electrode bodies todeliver a stimulation signal to a target nerve. In some non-limitingembodiments, the stimulation electrode 82 can comprise at least some ofsubstantially the same features and attributes as described within atleast U.S. Pat. No. 8,340,785 issued Dec. 25, 2012 and/or U.S. PatentApplication Publication No. 2011/0147046 published Jun. 23, 2011 theentire teachings of each of which are incorporated herein by referencein their entireties.

In some examples, the lead body 80 is a generally flexible elongatemember having sufficient resilience to enable advancing and maneuveringthe lead body 80 subcutaneously to place the stimulation electrode 82 ata desired location adjacent a nerve, such as an airway-patency-relatednerve (e.g. hypoglossal nerve, vagus nerve, etc.). In some examples,such as in the case of obstructive sleep apnea, the nerves may include(but are not limited to) the nerve and associated muscles responsiblefor causing movement of the tongue and related musculature to restoreairway patency. In some examples, the nerves may include (but are notlimited to) the hypoglossal nerve and the muscles may include (but arenot limited to) the genioglossus muscle. In some examples, lead body 80can have a length sufficient to extend from the IPG assembly 52implanted in one body location (e.g. pectoral) and to the targetstimulation location (e.g. head, neck). Upon generation via thecircuitry 62, a stimulation signal is selectively transmitted to theinterface block 68 for delivery via the stimulation lead 54 to suchnerves.

Returning to FIG. 1 , the implantable sensor 32 can assume various formsappropriate for implantation into a human patient, and generallyincludes a sensor component in the form of or akin to a motion-basedtransducer. In some embodiments, the motion-based transducer sensorcomponent of the implantable sensor 32 can be or include anaccelerometer (e.g., a single axis or multi-axis accelerometer), agyroscope, a pressure sensor, etc., as is known in the art. Theimplantable sensor 32 can provide information along a single axis, oralong multiples axes (e.g., three-axis accelerometer, three-axisgyroscope (three rotational axes), six-axis accelerometer (three linearaxes and three rotational axes), nine-axis accelerometer (three linearaxes, three rotational axes and three magnetic axes), etc. Regardless ofan exact form, the sensor component of the implantable sensor 32 iscapable of sensing, amongst other things, information indicative of aposture of the patient. As a point of reference, while informationgenerated by the implantable sensor 32 is signaled to and acted upon bythe posture module 34 as described below, information from theimplantable sensor 32 can be utilized by other modules or engines (e.g.,a therapy manager module that manages therapy delivered to the patientby the IMD 30 as described below).

The implantable sensor 32 can be connected to the IMD 30 in variousfashions. For example, and with additional reference to the IMD 50 ofFIG. 2 , the implantable sensor 32 can include a lead body carrying themotion-based transducer sensor element at a distal end, and a plug-inconnector at proximal end. The plug-in connector can be connected to theinterface block 66 (e.g., the interface block 66 can include or providea sense port sized and shaped to receive the plug-in connector of theimplantable sensor 32), and the lead body extended from the IPG assembly52 to locate the sensor element at a desired anatomical location.Accordingly, physical action-related information sensed via themotion-based transducer element is transmitted, via the interface block66, to the circuitry 62.

Alternatively, and as reflected by the block diagram of FIG. 3 , theimplantable sensor 32 can be physically coupled to the interface block66, and thus carried by the IPG assembly 52 (e.g., the implantablesensor 32 can be considered a component of the IMD 50). Among otherfeatures, this optional arrangement may eliminate tunneling and/or othersurgical steps ordinarily associated with placing sensing leads within apatient, as well as promote long term stability and ease securing theimplantable sensor 32 because it occurs in conjunction with securing theIPG assembly 52. In some embodiments, the physical coupling of theimplantable sensor 32 relative to the IPG assembly 52 is performed priorto implantation of those components.

In some embodiments, in order for the motion-based transducer-typeimplantable sensor 32 to fit on top of (e.g. next to) the housing 60 ofthe IPG assembly 52, a housing of the implantable sensor 32 has a sizeand shape that can maintain the motion-based transducer sensor componentin a fixed orientation relative to the IPG assembly 52. This arrangementfacilitates achieving and maintaining a proper orientation of themultiple orthogonal axes of the motion-based transducer sensor componentrelative to various axes of the patient's body, such as ananterior-posterior axis.

In related embodiments, and as reflected by the block diagram of FIG. 4, the implantable sensor 32 (and in particular the motion-basedtransducer sensor component as described above) can be incorporated intoa structure of the interface block 66 or into a structure of the housing60. With these and similar configurations, the sensor component of theimplantable sensor 32 is electronically connected to the circuitry 62within the housing 60 or other enclosure of the IPG assembly 52.

In yet other embodiments, the implantable sensor 32 can be incorporatedinto a structure of the stimulation lead 54. For example, FIG. 5 is ablock diagram schematically representing a stimulation lead 100including a stimulation electrode 102 and a motion-based transducersensor 104 (akin to the implantable sensor 32 described above),according to one example of the present disclosure. In some examples,the stimulation lead 100 comprises at least some of substantially thesame features and attributes as the lead 54 in FIG. 2 , except foradditionally including the motion-based transducer sensor 104. As shownin FIG. 5 , the lead 100 comprises a lead body 106 having a proximal end108 configured to be removably connectable to a port of an IPG assembly(e.g., the interface block 68 of the IPG assembly 52 of FIG. 2 ) and anopposite distal end 110 at which the motion-based transducer sensor 104and the electrode 102 are mounted. In some examples, the sensor 104 islocated closer to the distal end 106 than the proximal end 104 of thelead 100 without necessarily being at the distal end 110 of the leadbody 106. In some optional embodiments, a portion of the lead 100 atwhich the motion-based transducer sensor 104 is located includes amechanism (e.g., a rotatable sleeve) to enable selective rotation of themotion-based transducer sensor 104, which in turns enables adopting adesired orientation of the different axes 112 of the motion-basedtransducer sensor 104 (for example where the motion-based transducersensor 104 is a multi-axis accelerometer).

In yet other embodiments, the implantable sensor 32 can be wirelesslyconnected to the IMD 30. For example, FIG. 6 is a block diagramschematically representing a system including the IPG assembly 52 asdescribed above and a separate implantable sensor 150, according to oneexample of the present disclosure. The implantable sensor 150 comprisesat least some of substantially the same features and attributes as thepreviously described implantable sensors including the motion-basedtransducer sensor component, except for the lack of physical coupling ofthe implantable sensor 150 relative to IPG assembly 52; instead, theimplantable sensor 150 is electrically and communicatively coupledwirelessly relative to the IPG assembly 52. With this in mind, theinterface block 66 need not provide a sense port for the implantablesenor 150 or the sense port can be used for a second sensor (not shown).In some embodiments, the circuitry 62 of IPG the assembly 52 andcircuitry (not shown) of the implantable sensor 150 communicate via awireless communication pathway 152 according to known wirelessprotocols, such as Bluetooth, NFC, MICS, 802.11, etc. with each of thecircuitry 62 and the implantable sensor 150 including correspondingcomponents for implementing the wireless communication pathway 152. Insome examples, a similar wireless pathway is implemented to communicatewith devices external to the patient's body for at least partiallycontrolling the implantable sensor 150 and/or the IPG assembly 52, tocommunicate with other devices (e.g. other sensors) internally withinthe patient's body, or to communicate with other sensors external to thepatient's body as described in greater detail below.

Regardless of how the implantable sensor 32 is associated with the IPGassembly 52, in some embodiments the implantable sensor 32 is configuredto generate information indicative of sensed forces in three directionsor axes. For example, in some embodiments, the implantable sensor 32 isa three-axis accelerometer that can sense or measure the static and/ordynamic forces of acceleration on three axes. Static forces include theconstant force of gravity. By measuring the amount of staticacceleration due to gravity, logic or programming (e.g., software)acting upon information from an accelerometer sensor can figure out theangle the sensor is tilted at with respect to the earth. By sensing theamount of dynamic acceleration, logic or programming acting uponinformation from the accelerometer sensor can find out fast and in whatdirection the sensor is moving. Single- and multi-axis models ofaccelerometers detect magnitude and direction of acceleration (or properacceleration) as a vector quantity. With these and similar types ofsensor constructions, an output from the implantable sensor can includevector quantities in one, two or three axes. For example, FIG. 7Aprovides an axis orientation indicator 200 of a three-axis accelerometeruseful as the implantable sensor 32 in some non-limiting embodiments.The three axes and three outputs of the three-axis accelerometer areconventionally labeled as X, Y, and Z, with the three axes X, Y, Z beingorthogonal to one other. With these and related constructions, effortscan be made to implant the implantable sensor 32 within the patient'sbody such that the axes X, Y, Z are in general alignment with planes oraxes of the patient. For example, in FIG. 7B, a patient's body 202 canbe viewed as having a left side 204 and an opposite right side 206,along with an anterior portion 208 and an opposite posterior portion210. A conventional coordinate system of the patient's body 202 includesan anterior-posterior (A-P) axis and a lateral-medial (L-M) axis aslabeled in FIG. 7B, and a superior-inferior (S-I) axis (vertical orhead-to-toe) that is into a plane of the view of FIG. 7B. With thenon-limiting embodiment of FIG. 7B in which the implantable sensor 32 isa three-axis accelerometer disposed within the housing 60 of the IPGassembly 52, the implantable sensor 32 is arranged relative to thehousing 60 and the housing 60 arranged relative to the patient's body202 such that the sensor's X, Y, Z axes are approximately aligned withthe patient's body coordinate system. For example, the Z axis of theimplantable sensor can be aligned with A-P axis, the X axis aligned withthe L-M axis, and the Y axis aligned with the S-I axis. A posture(including position) of the patient can be designated with reference tothe body coordinate system, such that X, Y, Z information from thesensor 32 can be employed to determine posture when the sensor axes X,Y, Z are aligned with the body coordinate system axes. However, exactalignment can be difficult to achieve. Similar concerns may arise wherethe implantable sensor 32 is implanted at a location apart from thehousing 60 of the IPG assembly 52. As described below, some methods ofthe present disclosure can include calibrating information signaled fromthe implantable sensor 32 for possible misalignment with the bodycoordinate system axes or other concerns relating to determining ordesignating a posture of the patient based on information from theimplantable sensor 32. Calibration of the present disclosure can alsoaddress other possible concerns, such as the implantable sensor 32 (orthe IPG assembly 52 with embodiments in which the implantable sensor 32is carried in the housing 60) changing orientation relative to thepatient's body following implant. For example, with certain patients andimplant locations (e.g., high BMI patients, female patients, etc.), thepocket within which the device is implantable may shift between standingand laying down postures; calibration systems and methods of the presentdisclosure can account for these differences.

Returning to FIG. 1 , regardless of a format of the implantable sensor32, the posture module 34 is programmed to perform one or moreoperations as described below based upon information from theimplantable sensor 32 (e.g., the implantable senor 32 output is an inputto the posture module 34). In general terms, in some non-limitingexamples the posture module 34 is programmed to detect, determine ordesignate, based at least in part upon information signaled by theimplantable sensor 32, the current posture (including position) of thepatient. In other non-limiting examples, the posture module 34 isprogrammed to detect, determine or designate, based at least in partupon information signaled by the implantable sensor 32, that the patientis not in a particular posture (e.g., the patient is not supine). Asdescribed below, some non-limiting embodiments of the present disclosurerelate to methods for determining or designating the current posture,optionally including calibrating signaled information from theimplantable sensor 32. The posture module 34 is further programmed (orsignals information implicating the designated current posture toanother module or engine that is programmed) to perform one or moreoperations or routines relating to control of the system 20 (e.g.,controlling operations of the IMD 30, the implantable sensor 32, theexternal device 36, etc.) in some non-limiting embodiments. As describedbelow, some non-limiting embodiments of the present disclosure relate tomethods for acting upon the determined current posture. Othernon-limiting examples of the present disclosure related to methods foracting upon a determination that the patient is not in a particular ordesignated posture. The posture module 34 can be further programmed (orsignal information implicating the designated current posture to anothermodule or engine that is programmed) to provide information to thepatient and/or caregiver relating to the determined current posture (orother information of possible interest implicated by information fromthe implantable sensor 32). As described below, some non-limitingembodiments of the present disclosure relate to methods for generatingand/or reporting information to the patient and/or caregiver. Theposture module 34 (or the logic akin to the posture module 34 asdescribed below) can be incorporated into a distinct module or engineprogrammed to perform certain tasks (e.g., logic of the posture module34 as described below can be part of a therapy control engine andutilized in controlling stimulation therapy delivered to the patient).The posture module 34 (or the algorithms as described below) can residepartially or entirely with the IMD 30 (e.g., the circuitry 62 (FIG. 2)), partially or entirely with the external device 36, or partially orentirely with a separate device or component (e.g., the cloud, etc.).

Posture Determination

As implicated by the above, in some embodiments the posture module 34 isprogrammed or designed (e.g., appropriate algorithms) to detect,determine or designate a current posture of the patient based uponinformation from the implantable sensor 32. In at least this context,the term “posture” can refer at least to identifying whether a patientis in a generally vertical position or a lying down position, such as asupine position, a prone position, a left side position (e.g., leftlateral decubitus), a right side position (e.g., right lateraldecubitus), etc. In some instances, the term “posture” may sometimes bereferred to as “body position”.

In some examples, the posture module 34 rejects non-posture componentsfrom an accelerometer-type implantable sensor via low pass filteringrelative to each axis of the multiple axes of the accelerometer sensor.In some examples, posture is at least partially determined via detectinga gravity vector from the filtered axes.

In some examples, one potential posture classification protocolimplemented by the posture module 34 includes determining whether thepatient is active or at rest. In some examples, when a vector magnitudeof the acceleration measured via the accelerometer-type implantablesensor meets or exceeds a threshold (optionally for a period of time),the measurement may indicate the presence of non-gravitationalcomponents indicative of non-sleep activity. In some examples, thethreshold is about 1.15 G. Conversely, measurements of acceleration ofabout 1 G (corresponding to the presence of the gravitational componentsonly) may be indicative of rest.

In some examples, one potential posture classification protocolimplemented by the posture module 34 includes determining whether atleast an upper body portion (e.g., torso, head/neck) of the patient isin a generally vertical position (e.g., upright position) or lying down.In some examples, a generally vertical position may comprising standingor sitting. In some examples, this determination may observe the angleof the accelerometer-based implantable sensor between the Y axis and thegravitational vector, which sometimes may be referred to as ay-directional cosine. In some examples, when such an angle is less than40 degrees, the measurement suggests the patient is in a generallyvertical position, and therefore likely not asleep.

In some examples, if the measured angle (e.g., a y-directional cosine)is greater than 40 degrees, then the measured angle indicates that thepatient is lying down. In this case, one example posture classificationprotocol implemented by the posture module 34 includes classifyingsub-postures, such as whether the patient is in a supine position, aprone position, or in a lateral decubitus position. In some non-limitingexamples, after confirming a likely position of lying down, the postureclassification protocol determines if the patient is in a supineposition or a prone position. In some examples, the determination of asupine state is made when an absolute value of the z-directional cosine(the angle of the accelerometer-type implantable sensor between the Zaxis (calibrated to represent the A-P axis of the patient's body and thegravitational vector) is less than or equal to 45 degrees, and thedetermination of a prone state when the absolute value of thez-directional cosine is greater than or equal to 135 degrees. If neitherof those criteria are satisfied, then the patient may be lying on theirleft or right side (e.g., lateral decubitus position). Accordingly, insome non-limiting examples, the posture classification protocol performsa further classification via the pitch angle such that the patient isdesignated as lying on their right side if the pitch angle is less thanor equal to negative 45 degrees or greater than or equal to negative 135degrees; the patient is designated as lying on their left side if thepitch angle is greater than or equal to 45 degrees or the pitch angle isless than or equal to 135 degrees. In some examples, a similardetermination can be made using directional cosines.

The above explanations provide a few non-limiting examples of someposture determination or designation protocols implemented by theposture module 34. A number of other posture determination ordesignation techniques are also envisioned by the present disclosure,and can be function of the format of the implantable sensor 32 and/orother information provided by one or more additional sensors.

In some embodiments, the posture module 34 is programmed to distinguishbetween a supine sleep position and a generally supine reclinedposition. As a point of reference, a generally supine reclined positioncan be one in which the patient is on a recliner, on an adjustable-typebed, laying on a couch, or the like and not attempting to sleep (e.g.,watching television) vs. sleeping in bed. An absolute vertical distancebetween the head and torso of the patient in the supine sleep positionis less than the absolute vertical distance between the head and torsoin the generally supine reclined position. Alternatively or in addition,in some embodiments, the posture module 34 is programmed to consider orcharacterize a position of the patient's neck and/or head and/or bodyposition (e.g., as part of a determination of the patient's rotationalposition while lying down). For example, the posture module 34 can beprogrammed to estimate a position of the patient's neck based on bodyposition. A determination that the patient's torso is slightly offsetmay imply different head positions. In some non-limiting embodiments,the systems and methods of the present disclosure can consider orcharacterize a position of the patient's neck and/or head viainformation from a sensor provided with a microstimulator that isimplanted in the patient's neck or in conjunction with a sensorintegrated into the stimulation lead. In other examples, two (or more)position-type sensors (e.g., accelerometers) can be provided, eachimplanted in a different region of the patient's body (e.g., torso,head, neck) and providing information to the posture module 34sufficient to estimate neck and/or head and/or body positions of thepatient.

In addition to, or as an alternative to, the above, in some embodiments,the systems and methods of the present disclosure can include theposture module 34 programmed to determine or designate lying downpositions in addition to the four “primary” lying down positionsdescribed above (i.e., supine, prone, left lateral decubitus, and rightlateral decubitus). For example, and with additional reference to FIG. 8, the lying down positions can be classified or characterized asincluding supine 220, prone 222, left lateral decubitus 224, rightlateral decubitus 226, supine left 228, prone left 230, supine right232, and prone right 234. The posture module 34 can be configured orprogrammed to identify the lying down positions of FIG. 8 in variousmanners, for example where the implantable sensor 32 is a three-axisaccelerometer, the posture module 34 can be programmed to implement a 15degree radial offset to information received from the implantable sensor32 once a determination is made that the patient is lying down. A numberof other techniques can be employed, and the number of lying downpositions that can be classified by the posture module 34 is in no waylimited to the information implicated by FIG. 8 .

Additionally or alternatively, in some embodiments, the systems andmethods of the present disclosure can include the posture module 34programmed to determine or designate a current posture or position ofthe patient utilizing a temporal analysis or probabilistic basedapproached. For example, the posture module 34 can be programmed (e.g.,a time averaging algorithm) to designate a current posture or positionbased upon a time average of information from the implantable sensor 32,thus minimizing the impact of small artifacts in the information fromthe implantable sensor 32 due to, for example, arm movement, legmovement, jerking, etc., especially when the patient is sleeping. By wayof example, one approach for determining or designated that the patientis lying supine and sleeping can include reviewing a dot product ofvector information from the implantable sensor 32 (e.g., vectorinformation in a head-to-toe direction of the patient) with a gravity orvertical reference vector or head-to-toe (described in greater detailbelow); when the patient is lying supine and sleeping, this dot productwill be approximately zero. If the patient randomly jerks an appendagewhile sleeping, the dot product of corresponding vector information fromthe implantable sensor 32 with the gravity or vertical reference vectormay no longer be approximately zero yet the patient is still lyingsupine and asleep. By utilizing a time averaging or other probabilisticapproach, the posture module 34 will not designate a “new” posture orposition for the patient in response to the information generated by theimplantable sensor 32 at the time the patient jerks his/her appendage.However, in some embodiments, the temporal analysis or probabilisticapproach will be able to distinguish between the patient making a smallmovement while asleep and the patient rising from bed upon waking. Inrelated embodiments, motion artifacts can be filtered by considering anoverall magnitude of vector information from the implantable sensor 32over short periods of time. For example, where the patient is lying downand asleep, the overall magnitude of vector information from theimplantable sensor 32 will be approximately 1 g; if the patient jerks anappendage while sleeping, the overall magnitude will temporarily spike.Motion artifacts such as these can be filtered by ignoring temporaryspikes in overall magnitude of less than a predetermined period of time(e.g., a few seconds). In other embodiments, a low pass filter can beapplied to the implantable sensor signal to achieve similar results.

Additionally or alternatively, in some embodiments, the systems andmethods of the present disclosure can include the posture module 34programmed to determine or designate a current posture or position ofthe patient utilizing other probabilistic-based approaches. For example,the systems and methods can be programmed or operate an algorithm toperform an action when the probability that the patient is in aparticular posture exceeds a certain threshold. Low or high thresholdsmay be appropriate depending upon the function that will be triggered bythe detection. Likewise, the systems and method of the presentdisclosure optionally include taking an action when the probability thatthe patient is in a particular posture is below a particular threshold.In yet other examples, the systems and methods of the present disclosureinclude determining, based on information from the implantable sensor32, that the patient is not in a particular posture (e.g., the system isprogrammed to take an action when information from the implantablesensor 32 is designated by the posture module 34 as implicating that thepatient is not supine) or that the probability the patient is not in aparticular posture is above a threshold. By way of non-limiting example,some of the probabilistic-based approaches or techniques of the presentdisclosure can include correlating the likelihood of the patient notbeing in a particular posture with the likelihood of the patient beingin the particular posture. For example, where the “particular posture”is supine, a relationship of the probability of the patient not beingsupine (“not_probability_supine” can be correlated with the probabilityof the patient being supine (“probability_supine”) as:

not_probability_supine=1−probability_supine

In practice, there may be different error sources in determining“not_probability_supine” and “probability_supine”. For example, ifdifferent sensors or algorithms are used in the determination of each,the above equation would not hold and therefore, these two probabilitiesare distinct. This extends to the probability of multiple postureindications, each with a distinct error source. Also, the threshold(where applicable) that can be utilized for “not_probability_supine” maybe different than the threshold utilized with for “1—probability_supine” if, for example, there is an interest to add a biasto the algorithm to reduce sensitivity to one error source at theexpense of the other.

Additionally or alternatively, the systems and methods of the presentdisclosure can include calibrating to compensate, account, or addressthe possibility that a position of the implantable sensor 32 (from whichposture determinations can be made) within the patient's body is unknownand/or has changed over time (e.g., migration, temporary re-orientationdue to change in the implant pocket with changing posture as mentionedabove). In some examples, the posture module 34 can be programmed (e.g.,algorithm) to perform such calibration, such as when the patient isdetermined to be walking because such a behavior is consistent with agravity vector (e.g., of an accelerometer optionally used as theimplantable sensor 32) pointing downward. In some examples, the posturemodule 34 can be programmed to perform a calibration, such as viameasuring a gravity vector in at least two known patient orientations,of the implantable sensor/accelerometer 32 orientation. In someembodiments, where the output of the implantable sensor 32 is employedto detect postures of the patient in terms of the body coordinate systemof the patient and the orientation of the implantable sensor 32 is suchthat the implantable sensor axes are not aligned with the body axes, acalibration can be applied to information provided by the implantablesensor 32 to a correct or account for this misalignment.

In some embodiments, calibration performed by the posture module 34 caninclude establishing or creating a vertical baseline gravity vector. Forexample, the vertical baseline gravity vector can be determined by theposture module 34 during times when the patient is deemed to be likelyby upright (e.g., based on various information such as information fromthe implantable sensor, information from other sensors, time of day,patient history, etc., the likelihood or probability that the patient isupright and/or is engaged in an activity in which the patient is likelyto be upright (e.g., walking) can be determined), and can be determinedas a time average value during periods of higher activity. Onceestablished, the vertical baseline gravity vector can be utilized by theposture module 34 to calibrate subsequently-received information fromthe implantable sensor 32. The vertical baseline gravity vector can bedetermined/re-set periodically (e.g., at pre-determined intervals).

In addition or alternatively, calibration performed by the posturemodule 34 can include establishing or creating a horizontal baselinegravity plane (alternatively a horizontal baseline vector or“head-to-toe” vector (relative to the patient's anatomy)). As a point ofreference, the “vertical gravity vector” can be considered a vectortruly aligned with the direction of gravity relative to earth. A“horizontal gravity plane” can be considered the plane that is trulyorthogonal to the vertical gravity vector; a horizontal gravity vector(such as a head-to-toe vector) can be considered a vector that liessolely in the horizontal gravity plane. With this in mind, in someembodiments, the horizontal baseline gravity plane can be determined bythe posture module 34 during times when the patient is deemed to belikely by lying down (e.g., based on various information such asinformation from the implantable sensor 32, information from othersensors, time of day, patient history, etc., the likelihood orprobability that the patient is lying down and/or is engaged in a lowactivity in which the patient is likely to be lying down (e.g.,sleeping) can be determined), and can be determined as a time averagevalue during periods of low activity. Once established, the horizontalbaseline gravity plane can be utilized by the posture module 34 tocalibrate subsequently-received information from the implantable sensor32. The horizontal baseline gravity plane can be determined/re-setperiodically (e.g., at pre-determined intervals). In some embodiments,the horizontal baseline gravity plane can be determined by the crossproduct of various vectors obtained during periods of low activity so asto reduce or eliminate artifacts from rotation (e.g., the patient islying down and changes positions from back, stomach, side, etc.). Thecross product of two vectors obtained from the implantable sensor 32when it is believed the patient is lying down should approximately equalthe vertical baseline gravity vector; under circumstances where this isnot true, it can be assumed that one or both of the vectors underconsideration are not indicative of the patient in a lying down positionand thus less useful in determining or designating a horizontal baselinegravity plane (or used as a horizontal baseline gravity vector).

In addition or alternatively, calibration performed by the posturemodule 34 can include establishing or creating a vertical baselinegravity vector and a horizontal baseline gravity plane (or horizontalbaseline gravity vector otherwise within the horizontal baseline gravityplane) as described above (and useful for calibrating information fromthe implantable sensor 32 as part of a posture characterization ordetermination process), and confirming usefulness of the so obtainedcalibration values. For example, a dot product of a designated verticalbaseline gravity vector and a designated vector of the horizontalbaseline gravity plane is generated and compared to a threshold value.From this comparison, a usefulness of one or both of the designatedvertical baseline gravity vector and the designated horizontal baselinegravity plane (or designated horizontal baseline gravity vector) isgenerated. For example, if the dot product is close to zero, then one orboth of the designated vertical baseline gravity vector and thedesignated horizontal baseline gravity vector (or plane) are verified,and can be employed for calibrating information from the implantablesensor 32.

In addition or alternatively, calibration performed by the posturemodule 34 can include receiving a predetermined vertical baselinegravity vector and one or more predetermined horizontal baseline gravityvectors (e.g., indicative of prone, supine, left lateral decubitus,right lateral decubitus) useful for calibrating information from theimplantable sensor 32. The predetermined baseline gravity vectors can beentered during the implant procedure (e.g., entered by a clinician usingthe external device 36 in the operating room), as part of a programmingappointment (e.g., following implant, the patient mimics each posture orposition of interest, and the posture module 34 is prompted (e.g., viathe external device 36) to denote the corresponding vector informationfrom the implantable sensor 32 as being the predetermined baselinegravity vector), as part of an in-home calibration procedure performedby the patient (e.g., the external device 36 is a smart phone or thelike operating a software application), etc. In some embodiments, theposture module 34 is programmed to confirm the usefulness of theso-generated, predetermined baseline gravity vectors. For example, dotproducts and/or cross products of respective pairs of the predeterminedbaseline gravity vectors can be obtained to error check and ensure thatall the predetermined baseline gravity vectors are approximatelyperpendicular (i.e., within 5 percent of a truly perpendicularrelationship). To the extent any predetermined baseline gravityvector(s) are found to not be approximately perpendicular, thepredetermined baseline gravity vector(s) can be further reviewed forpossible usefulness as a calibration factor, or other steps taken toobtain viable predetermined baseline gravity vector(s). Conversely, tothe extent the error check confirms viability of the predeterminedbaseline gravity vectors, the predetermined baseline gravity vectors canthen be employed for calibrating information from the implantable sensor32. In yet other embodiments, the posture module 34 can be programmedsuch that if the vectors are compared to reference vectors and thereappears to be differences, a notification can be provided to the patientand/or clinician to re-preform the predetermined baseline gravity vectorentry procedures.

In addition or alternatively, calibration performed by the posturemodule 34 can include determining an orientation of the implantablesensor 32 in the patient's body based upon respiratory and/or cardiacwaveform polarity information provided by or derived from theimplantable sensor 32 and/or other appropriate sensor componentsassociated with the patient. In one aspect, motion signals have asignificantly greater amplitude than respiration signals, and thereforethe motion signals are extracted from a respiratory waveform orotherwise rejected. In some examples, this extraction may be implementedvia an awareness of motion associated with an X axis or Y axis of anaccelerometer sensor having signal power significantly greater than thesignal power of a Z axis in the accelerometer sensor, such as where theaccelerometer sensor is implanted in some examples such that its Z axisis generally parallel to an anterior-posterior axis of the patient'sbody. If a patient's respiration signal is largest in a particular axis(not necessarily aligned with one of X, Y, Z), motion artifact can berejected by filtering signals not aligned with the axis whererespiration is largest. In one aspect, motion signals sensed via theaccelerometer sensor can be distinguished from the respiration signalssensed via the accelerometer according to the high frequency contentabove a configurable threshold. The respiratory and/or cardiac waveformpolarity information can, for example, be reviewed to determine alikelihood of the patient being asleep (and thus lying down) and/or todetermine a likelihood of the patient engaged in higher activity (andthus upright). Upon determining that the patient is currently likelylying down and/or likely upright, the posture module 34 can beprogrammed to review current information from the implantable sensor 32;to the extent the current information is not aligned with the determinedlikely position (e.g., it is determined that the patient is likely lyingdown and the current information from the implantable sensor 32 (e.g.vector information) does not directly implicate the patient is lyingdown), a calibration factor can be determined by the posture module 34to be applied to information from the implantable sensor 32 based upondifferences between the current information and expected.

In addition or alternatively, calibration performed by the posturemodule 34 can include determining an expected change in information fromthe implantable sensor 32 upon waking. Based upon information (currentand/or tracked/historical) from the implantable sensor 32 and/or one ormore additional sensors associated with the patient, it can bedetermined when the patient is likely asleep (and thus lying down) andwhen the patient is likely waking from sleep and changing to an uprightposture (e.g., the patient gets out of bed in the morning following anight's sleep). Upon determining that the patient is currently likelychanging posture upon waking from sleep, the posture module 34 can beprogrammed to review current information from the implantable sensor 32;to the extent the current information is not aligned with the determinedlikely position (e.g., it is determined that the patient is likelycurrently upright and the current information from the implantablesensor 32 (e.g., vector information) does not directly implicate thepatient is upright), a calibration factor can be determined by theposture module 34 to be applied to information from the implantablesensor 32 based upon differences between the current information andexpected.

In addition or alternatively, calibration performed by the posturemodule 34 can include reviewing current information from the implantablesensor 32 when the patient is likely asleep (and thus likely lyingdown). For example, the posture module 34 can incorporate, or receivedinformation from, an internal clock. With reference to information fromthe internal clock, the posture module 34 can be programmed to designatethat the patient is likely lying down during certain hours of the day(e.g., 9:00 PM-7:00 AM, etc.). The “likely lying down” time frame can bepre-programmed to the posture module 34 and/or can be learned over time(based upon tracked/historical information). Upon determining that thepatient is likely currently lying down, the posture module 34 can beprogrammed to review current information from the implantable sensor 32;to the extent the current information is not aligned with the determinedlikely position (e.g., it is determined that the patient is likelycurrently lying down and the current information from the implantablesensor 32 (e.g. vector information) does not directly implicate that thepatient is lying down), a calibration factor can be determined by theposture module 34 to be applied to information from the implantablesensor 32 based upon differences between the current information andexpected.

In addition or alternatively, calibration performed by the posturemodule 34 can include referencing information generated by a patientcalibration program following implant. The patient calibration programcan be implemented as part of a software application operated by theexternal device 36 (e.g., the external device 36 can be a smartphone orthe like operating a software application programmed to effect patientcalibration, a custom external programmer operating a patientcalibration routine, a remote control, etc.), and walks the patientthrough a calibration sequence in which the patient is prompted toassume various postures or positions of interest; while the patient isin a particular posture or position, the posture module 34 is promptedto denote the current information from the implantable sensor 32 ascorresponding to that particular posture or position. The results ofthis calibration sequence can be used to calibrate, adjust or correctinformation subsequently provided by the implantable sensor 32 and/or to“teach” the posture module 34 different orientations of the implantablesensor 32 relative to the patient. In some embodiments, the softwareapplication is programmed to prompt the patient to assume a verticalposition and receive an indication that the patient is in the verticalposition for establishing the predetermined vertical baseline gravityvector. Alternatively or in addition, the software application isprogrammed to prompt the patient to assume a horizontal supine positionand receive an indication that the patient is in the horizontal supineposition for establishing the predetermined horizontal supine baselinegravity vector. Other baseline vectors can be determined from theso-established predetermined horizontal supine baseline gravity vector(e.g., a predetermined horizontal prone baseline gravity vector, apredetermined horizontal left lateral decubitus baseline gravity vector,a predetermined horizontal right lateral decubitus baseline gravityvector, etc.). In yet other embodiments, the software application can beprogrammed to prompt the patent to assume one or more of a verticalposition, a horizontal prone position, a horizontal left lateraldecubitus position, and a horizontal right lateral decubitus positionand receive a corresponding indication from the patient for establishingthe predetermined vertical baseline gravity vector, the predeterminedhorizontal prone baseline gravity vector, the predetermined horizontalleft lateral decubitus baseline gravity vector, and the predeterminedhorizontal right lateral decubitus baseline gravity vector.

In addition or alternatively, calibration performed by the posturemodule 34 can include a clinician programing at least one patientposition to the posture module 34 while the patient is in the operatingroom (e.g., during the implantation procedure). For example, theclinician can program the posture module 34 that the patient iscurrently lying down position. Upon being information that the patientis currently lying down (or some other posture or position), the posturemodule 34 can be programmed to review current information from theimplantable sensor 32; to the extent the current information is notaligned with a lying down positon (e.g., the current information fromthe implantable sensor 32 (e.g., vector information) does not directlyimplicate that the patient is lying down), a calibration factor can bedetermined by the posture module 34 to be applied to information fromthe implantable sensor 32 based upon differences between the currentinformation and expected.

Operational Control

As alluded to above, in some non-limiting embodiments, the posturemodule 34 is programmed to control one or more operational features ofthe system 20 based upon a determined or designated posture (orcommunicates with another module or engine programmed to control anoperational feature based upon posture as determined or designated bythe posture module 34).

For example, the posture module 34 can be programmed (or communicateswith another module or engine that is programmed) to select or implementa particular operational mode of the IMD 30 based upon the determinedcurrent posture. The “operational mode” of the IMD 30 can include one ormore of stimulation parameters, sensing parameters, timing parameters,and diagnostic parameters. For example, the posture module 34 (oranother module or engine provided with the system 20 and receivingposture information from the posture module 34) can be programmed withvarious, pre-determined stimulation therapy settings or modesappropriate for different sleeping positions of the patient (e.g.,stimulation therapy settings or mode for one sleeping position (supine,prone, left lateral decubitus, right lateral decubitus, etc.) can differfrom that of another sleeping position). When the posture module 34determines that the patient is in a particular position, the IMD 30 isoperated to implement the corresponding stimulation therapy settings ormode. With these and related embodiments, the posture module 34 (oranother module or engine provided with the system 20 and receivingposture information from the posture module 34) can be programmed toautomatically toggle operation of the IMD 30 between stimulation therapysettings in response to determined changes in the patient's posture. Inyet other optional embodiments, the posture module 34 is programmed todetermine a dot product value from vector information provided by theimplantable sensor 32 as a threshold parameter for initiating (orsuspending) delivery of therapy from the IMD 30. In yet other optionalembodiments, when the posture module 34 determines that the patient isnot in a particular posture or position, the IMD 30 is operated toimplement a designated mode or stimulation therapy settings. With theseand related embodiments, the posture module 34 (or another module orengine provided with the system 20 and receiving posture informationfrom the posture module 34) can be programmed to automatically toggleoperation of the IMD 30 between stimulation therapy settings in responseto determination that the patient is not in a particular posture. In yetother optional embodiments, the systems and methods of the presentdisclosure include monitoring for the patient assuming various posturesin a particular order, and then triggering a designated function whenthe ordering of postures is found to have occurred. With any of theexamples of operational control described in the present disclosure, theparticular control feature can be implemented upon determining orestimating that the patient is in a particular posture, or upondetermining or estimating that the patient is not in a particularposture.

Additionally or alternatively, in some embodiments the posture module 34can be programmed (or communicates with another module or engine of thesystem 20 that is programmed) to effect changes to a particular therapybeing delivered to the patient by the IMD 30 based upon the determinedposture and optionally other factors, akin to auto-titration. With theseand related embodiments, the posture module 34 (or another module orengine of the system 20 communicating with the posture module 34) can,for example, automatically increase or decrease one or more parametersof a particular stimulation therapy mode, for example upon identifyingthat the patient is entering a different stage of sleep. In someexamples, the posture module 34 (or another module or engine of thesystem 20 communicating with the posture module 34) incorporatesalgorithm(s) or programming to effect posture-based, automatic amplitudeadjustments, providing a relatively consistent correlation betweentherapeutic amplitude and determined posture.

As a point of reference, stages of sleep are typically divided intonon-rapid eye movement (non-REM) and rapid eye movement (REM). Non-REMsleep has three stages: N1, N2, and N3. N1 occurs right after fallingasleep, and is typically characterized as “light sleep”. During sleep, aperson usually progresses through the three stages of non-REM sleepbefore entering REM sleep or stage. Obstructive sleep apnea may be lessprevalent in N1 than REM.

Additionally or alternatively, in some embodiments the posture module 34can be programmed (or communicates with another module or engine of thesystem 20 that is programmed) to effect changes to a particular therapybeing delivered to the patient by the IMD 30 under circumstances wherethe patient is likely in a light state of sleep (e.g., N1), as derivedfrom information of the implantable sensor 32. For example, the posturemodule 34 can be programmed to identify when the patient is likelyasleep or attempting to sleep, and track changes in the patient'sposture or position during the time the patient is deemed to be sleepingor attempting to sleep. Under circumstances where the system 20 isprogrammed to deliver therapy to the patient when the patient issleeping, the posture module 34 (or another module or engine of thesystem 20 communicating with the posture module 34) can further beprogrammed to alter the currently-delivered therapy when the patient isdetermined to be changing positions while likely sleeping. For example,where it is determined that the patient has changed positions, orchanged positions two or more times over a pre-determined time period(e.g., 5 minutes, 15 minutes, 30 minutes, etc.), it is likely that thepatient is in a light state of sleep and that if stimulation therapywere continued to be delivered at pre-determined levels, thisstimulation may make it more difficult for the patient to enter a deeperstate of sleep. With these and other examples, the posture module 34 (oranother module or engine of the system 20 communicating with the posturemodule 34) can be programmed to prompt the IMD 30 to pause thestimulation therapy being delivered to the patient and/or ramp down anintensity of the stimulation therapy being delivered to the patient. A“pause” can be considered a rapid ramping down to no stimulation therapybeing delivered in some embodiments. The pause or ramping down can beeffected for a pre-determined period of time or some other parameter(e.g., respiratory cycles, determination of unchanged sleep posture),and the IMD 30 prompted to re-commence or ramp up the stimulationtherapy delivered to the patient.

Additionally or alternatively, in some embodiments the posture module 34can be programmed (or communicates with another module or engine of thesystem 20 that is programmed) to effect changes to a particular therapybeing delivered to the patient by the IMD 30 under circumstances wherethe patient is likely temporarily exiting a state of sleep, as derivedfrom information of the implantable sensor 32. For example, the posturemodule 34 can be programmed to identify when the patient is likelyasleep or attempting to sleep, and track changes in the patient'sposture or position during the time the patient is deemed to be sleepingor attempting to sleep. Under circumstances where the system 20 isprogrammed to deliver therapy to the patient when the patient issleeping, the posture module 34 (or another module or engine of thesystem 20 communicating with the posture module 34) can further beprogrammed to alter the currently-delivered therapy when the patient isdetermined to be likely temporarily exiting a state of sleep. Forexample, during the time period when the patient is normally sleeping,the patient may wake up and move to go to the bathroom, get a drink ofwater, etc. If stimulation therapy were continued to be delivered atpre-determined levels during the temporary exit from sleep, thisstimulation may be undesirable for the patient. Thus, in someembodiments, where it is determined that the patient has a substantivechange in posture during the time period when the patient is expected tobe asleep, the posture module 34 (or another module or engine of thesystem 20 communicating with the posture module 34) can be programmed toprompt the IMD 30 to pause the stimulation therapy being delivered tothe patient and/or ramp down an intensity of the stimulation therapybeing delivered to the patient. In related embodiments, the pause orramping down can be effected for a pre-determined period of time, andthe IMD 30 prompted to re-commence or ramp up the stimulation therapydelivered to the patient; alternatively or in addition, the delivery ofstimulation therapy can be re-commenced or ramped up upon determiningthat the patient has returned to a lying down position, automaticallyfollowing expiration of a predetermined time period, followingexpiration of a predetermined time period and a determination that thepatient is not moving about (e.g., an “auto-extended” pause), etc.

With optional embodiments described above in which the posture module 34operates to effect an automatic pause or ramp down in delivered therapyfor a predetermined time period, the posture module 34 can further beprogrammed (or communicates with another module or engine of the system20 that is programmed) to incorporate or implement a pause or ramp downextension at the end of the predetermined time period undercircumstances where it is determined that the patient is not in a sleepposture, is moving about, etc. In other optional embodiments, theposture module 34 (or another module or engine of the system 20communicating with the posture module 34) is programmed to provide anauto-pause feature coupled to an automatic start time feature. Forexample, the system 20 can be programmed to initiate delivery of therapyat a predetermined time of day (e.g., 10:30 PM), but at thepredetermined time of day after which stimulation therapy is to bedelivered, this automatic start time is automatically paused until it isestimated or determined (e.g., information from the implantable sensor32 via the posture module 34) that the patient is, or is likely, asleep.

Additionally or alternatively, in some embodiments the posture module 34can be programmed (or communicates with another module or engine of thesystem 20 that is programmed) to perform an alert-type operation orroutine under circumstances where the patient is likely in a position ofpoor sleep quality (and thus more likely to experience sleep disorderedbreathing), as derived from information of the implantable sensor 32.For example, the posture module 34 can be programmed to identify whenthe patient is likely asleep or attempting to sleep, and when thepatient is determined to be in a particular posture or position (e.g.,supine) based upon information from the implantable sensor 32, theposture module 34 (or another module or engine provided with the system20 and communicating with the posture module 34) is programmed to promptdelivery of an inconvenient output to the patient intended to cause orencourage the patient to re-orient. For example, the IMD 30 can beprompted to increase the level of a currently-delivered stimulationtherapy, prompted to deliver rapid multi-pulse stimulation, etc.Alternatively or in addition, the IPG assembly 52 can be prompted tovibrate. Alternatively or in addition, an audio alert can be generatedat one or both of the IPG assembly 52 and the external device 36.

Additionally or alternatively, in some embodiments the posture module 34can be programmed (or communicates with another module or engine of thesystem 20 that is programmed) to one or more of initiate, resume or rampup (e.g., increase intensity) of delivered stimulation therapy upondetermining that the patient has entered, or is likely to have entered,a state of sleep. For example, the posture module 34 can estimate ordetermine a plurality of current postures of the patient over time.Based upon stored algorithms or other predetermined parameters, when theplurality of postures implicates that the patient has entered a state ofsleep, the posture module 34 prompts the IPG assembly 52 to begindelivering stimulation therapy. In related embodiments in which theposture module 34 is programmed to affect an “auto-pause” in deliveredstimulation therapy (e.g., in response to a determination that thepatient is awake or in a state of light sleep), the posture module 34 isprogrammed to prompt resuming of the stimulation therapy upondetermining that the patient has, or has likely, entered a state ofsleep based, at least in part, upon the posture information. In otherrelated embodiments in which the system 20 is programmed to ramp downcurrently-delivered stimulation therapy under one or more circumstances(e.g., in response a determination that the patient is awake or in astate of light sleep), the posture module 34 is programmed to promptramping up of the stimulation therapy upon determining that the patienthas, or has likely, entered a state of deep or deeper sleep based, atleast in part, upon the posture information.

Additionally or alternatively, in some embodiments the posture module 34can be programmed (or communicates with another module or engine of thesystem 20 that is programmed) to effect changes to therapy protocols ormodes or other therapy parameters based upon learned or detectedtendencies (e.g., sleep tendencies) of the patient over time as derived,at least in part, from information of the implantable sensor 32. Forexample, the posture module 34 (or another module or engine of thesystem 20 communicating with the posture module 34) can be programmed totrack or record posture (or other information) during times when thepatient is deemed to likely be asleep; the tracked information caninclude, for example, time of day, day of week, and the like. From thisinformation, the posture module 34 can determine, over time (e.g., oneor more days, weeks, or months), the patient's sleeping tendencies, forexample the time periods the patient typically sleeps. The learned sleeptendencies determined by the posture module 34 can further be segmentedby day of the week or consecutive days of the week (e.g., sleeptendencies on weekends and sleep tendencies on weekdays). The posturemodule 34 (or another module or engine of the system 20) can further beprogrammed to review a current time of day, a current day of week, orother sleep tendency parameter along with a current designated postureof the patient with the learned sleep tendency information to promptoperation of the IMD 30 (e.g., to initiate or end the delivery oftherapy, such as stimulation therapy). For example, a current time ofday and determined current posture can be recorded as a data pair, andcompared with previously recorded sleep tendency information todetermine whether the current time of day and current posture implicatesthat the patient is likely entering a state of sleep or exiting a stateof sleep. Based upon this comparison, the IMD 30 can be prompted toinitiate delivery of therapy (where the patient is likely entering astate of sleep) or end delivery of therapy (where the patient is likelyexiting a state of sleep). Alternatively or in addition, the current dayof week, current time of day, and current posture can be recorded as adata set, and compared with previously recorded sleep tendencyinformation to determine whether the current time of day, current day ofweek and current posture implicates that the patient is likely enteringa state of sleep or exiting a state of sleep. Based upon thiscomparison, the IMD 30 can be prompted to initiate delivery of therapy(where the patient is likely entering a state of sleep) or end deliveryof therapy (where the patient is likely exiting a state of sleep).

Additionally or alternatively, in some embodiments the posture module 34can be programmed (or communicates with another module or engine of thesystem 20 that is programmed) to determine contextual information of thepatient during periods when the patient is awake as derived, at least inpart, from information of the implantable sensor 32. For example,contextual information such as activity level, pelvic floor pressure,etc., can be determined or estimated based upon posture relatedinformation alone or in combination with additional, non-postureinformation.

Diagnostic Data

As alluded to above, in some non-limiting embodiments, the posturemodule 34 is programmed to provide information to the patient and/orcaregiver relating to the determined current posture or otherinformation of possible interest implicated by information from theimplantable sensor 32, for example via the external device 36. As apoint of reference, the IMD 30 can be configured to interface (e.g., viatelemetry) with a variety of external devices. For example, the externaldevice 36 can include, but is not limited to, a patient remote, aphysician remote, a clinician portal, a handheld device, a mobile phone,a smart phone, a desktop computer, a laptop computer, a tablet personalcomputer, etc. The external device 36 can include a smartphone or othertype of handheld (or wearable) device that is retained and operated bythe patient to whom the IMD 30 is implanted. In another example, theexternal device 36 can include a personal computer or the like that isoperated by a medical caregiver for the patient. The external device 36can include a computing device designed to remain at the home of thepatient or at the office of the caregiver.

With the above in mind, the posture module 34 can be programmed (orcommunicates with another module or engine of the system 20 that isprogrammed) to identify information from the implantable sensor 32indicative of the occurrence of twiddler's syndrome. “Twiddler'ssyndrome” refers to the patient's deliberate or subconscious spinning orother manipulation of the IPG assembly 52 within the skin pocket, andcan lead to malfunction of the IMD 30. For example, logic (e.g.,algorithm) of the posture module 34 can recognize a substantive changein information from the implantable sensor 32 at, for example, adesignated time of day. By way of non-limiting example, a time of daycan be designated as the patient likely being in a lying down positionor posture (e.g., 1:00 AM); where the information from the implantablesensor 32 is found to have a certain vector direction on a previous dayat the designated time of day (or over several consecutive previous daysat the designated time of day) and a substantively different vectordirection on the current day at the designated time of day (e.g., anapproximately opposite vector direction), it can be deemed there is alikelihood that the implantable sensor 32 has been flipped. Where theimplantable sensor 32 is carried in the housing of the IPG assembly 52,this same information can be deemed as implicating a likelihood that theIPG assembly 52 has been flipped. Under these and similar circumstance,the posture module 34 can be programmed to notify or alert a clinician(via the external device 36) of the likely occurrence of twiddler'ssyndrome.

Alternatively or in addition, the posture module 34 can be programmed(or communicates with another module or engine of the system 20 that isprogrammed) to identify information from the implantable sensor 32indicative of the occurrence of device migration. As a point ofreference, in some embodiments the sensor component of the implantablesensor 32 is implanted in the patient apart from the IPG assembly 52,whereas in other embodiments the implantable sensor 32 is carried in thehousing of the IPG assembly 52 that in turn is implanted in the patient.Regardless, common implantation techniques can include use of suture orsimilar attachment device that secures the device in question (e.g., thesensor component or the IPG assembly 52) to anatomy of the patient; overtime, attachment between the device and the anatomy in question maylessen or deteriorate, with the device then migrating away from theexact implant location and/or orientation. With this in mind, logic(e.g., algorithm) of the posture module 34 can recognize changes ininformation from the implantable sensor 32 at, for example, a designatedtime of day, as implicating possible device migration. By way ofnon-limiting example, a time of day can be designated as the patientlikely being in a lying down position or posture (e.g., 1:00 AM); wherethe information from the implantable sensor 32 is found to have acertain vector direction that is changing over time, it can be deemedthere is a likelihood that the implantable sensor 32 has migrated froman initial implant location. Where the implantable sensor 32 is carriedin the housing of the IPG assembly 52, this same information can bedeemed as implicating a likelihood that the IPG assembly 52 has beenmigrated. Under these and similar circumstance, the posture module 34can be programmed to notify or alert a clinician (via the externaldevice 36) of the likely occurrence of device migration.

Alternatively or in addition, the posture module 34 can be programmed(or communicates with another module or engine of the system 20 that isprogrammed) to record posture-related information during certainactivities of the patient and report the same to a clinician and/or thepatient via the external device 36. For example, the posture module 34can record or determine one or more of the percent of time the patientspends in each position during a sleeping event; the efficacy of therapydelivered by the IMD 30 in each position during a sleeping event;auto-titrated therapy setting (e.g., amplitude, electrode configuration,pulse characteristics, etc.) in each position during a sleeping event;etc. In related embodiments, the posture module 34 can operate (orcommunicate with) a sleep stage determination engine by which sleepstages can be determined. In some embodiments, such determination ismade according to the relative stability of respiratory rate throughoutthe treatment period (e.g., during expected sleeping hours). In somenon-limiting examples, the sleep determination engine determines andtracks the number of minutes awake, minutes in bed, posture, sleep/wakecycle, and/or number and depth of REM periods. In some examples, theposture module 34 can operate (or communicate with) a sleep qualityengine to determine sleep quality according to, for example, acombination of a sleep time parameter, a sleep stage parameter, and aseverity index parameter (e.g., apnea-hypopnea index measurement). Thesleep stage can be determined via at least one of activity information,posture information, respiratory information, respiratory ratevariability (RRV) information, heart rate variability (HRV) information,and heart rate information in some non-limiting embodiments. Otherinformation that can be tracked by the posture module 34 (or othermodule or engine of the system 20) and delivered to a clinician and/orthe patient via the external device 36 can include one or more ofapnea-hypopnea index, respiratory rate, sleep disordered breathing,peripheral capillary oxygen saturation (SpO2), heart rate, snoring, etc.In yet other embodiments, the posture module 34 can be programmed togenerate posture notifications at the external device 36 whenstimulation (or other therapy) is being provided by the IMD 30.

Alternative Operational Modes

In some non-limiting examples of the present disclosure, the posturemodule 34 is programmed to detect a change in posture, and need notnecessarily detect or designate a current posture of the patient (undersome circumstances or under all circumstances). For example, the posturemodule 34 can be programmed or configured (e.g., operating logic oralgorithm) such that when the patient is deemed or known to be asleep,the posture module 34 does not detect or designate a current posture ofthe patient (nor does any other module or engine of the system butdetects changes in posture, such as gross changes in posture (e.g.,moving from left lateral decubitus to supine, supine to prone, etc.).

In other embodiments, the posture module 34 does not detect or determineposture (nor does any other module or engine of the system 20), buttracks the gravity vector of the implantable sensor 32 over time. Withthese and related embodiments, the posture module 34 is programmed orconfigured to allow a user (e.g., patient, caregiver, etc.) to definecertain gravity vector orientations relative to the implantable sensor32 (or relative to the IPG assembly 52 where the implantable sensor 32is carried in the housing of the IPG assembly 52) that can be associatedwith different operations modes. Any number of these definedvector/modes could be established with variable ranges of affect. By wayof non-limiting example, the posture module 34 (or other module orengine of the system can be programmed or configured to activate therapydelivery during a defined time period when no or minimal motion by thepatient is detected, and the monitored gravity vector (or othermonitored patient information related to posture) is within apredetermined range.

In addition or alternatively, changes in the monitored gravity vector ofa certain or pre-determined magnitude can be used to reset a therapyramp (e.g., therapy is being delivered at a predetermined level orintensity, and a detected change in the monitored gravity vector issufficient to prompt the ramping down of the delivered therapy level;delivery of the ramped down or lower level therapy continues until themonitored gravity vector returns to the predetermined range (e.g.,implicating that the “change” in the patient's status is complete) andthe delivered therapy is ramped up to the predetermined level orintensity). In other embodiments, when monitoring the gravity vectorover time, the system can be programmed to make therapy changes based onat least one of the current vector, a change in the vector (e.g.,vector, cosine math), or repeating change in the vector (e.g.,implicating walking, breathing, etc.).

As implicated by the above descriptions, one or both of the IMD 30 andthe external device 36 includes a controller, control unit, or controlportion that prompts performance of designated actions. FIG. 9A is ablock diagram schematically representing a control portion 300,according to one example of the present disclosure. In some examples,the control portion 300 includes a controller 302 and a memory 304. Insome examples, the control portion 300 provides one exampleimplementations of a control portion forming a part of, implementing,and/or managing any one of devices, systems, assemblies, circuitry,managers, engines, functions, parameters, sensors, electrodes, modules,and/or methods, as represented throughout the present disclosure inassociation with FIGS. 1-8 .

In general terms, the controller 302 of the control portion 300comprises an electronics assembly 306 (e.g., at least one processor,microprocessor, integrated circuits and logic, etc.) and associatedmemories or storage devices. The controller 302 is electricallycouplable to, and in communication with, the memory 304 to generatecontrol signals to direct operation of at least some the devices,systems, assemblies, circuitry, managers, modules, engines, functions,parameters, sensors, electrodes, and/or methods, as representedthroughout the present disclosure (e.g., the posture module 34 (FIG. 1 )can be a software program stored on a storage device, loaded onto thememory 304, and executed by the electronics assembly 306). In addition,and in some examples, these generated control signals include, but arenot limited to, employing therapy manager 308 stored in the memory 304to at least manage therapy delivered to the patient, for example therapyfor sleep disordered breathing, and/or manage and operate designatedphysical action sensing in the manner described in at least someexamples of the present disclosure. It will be further understood thatthe control portion 300 (or another control portion) may also beemployed to operate general functions of the various therapydevices/systems described throughout the present disclosure.

In response to or based upon commands received via a user interface(e.g. user interface 310 in FIG. 9C) and/or via machine readableinstructions, the controller 302 generates control signals to implementtherapy implementation, therapy monitoring, therapy management, and/ormanagement and operation of designated physical action sensing andcontrol in accordance with at least some of the previously describedexamples of the present disclosure. In some examples, the controller 302is embodied in a general purpose computing device while in someexamples, the controller 302 is incorporated into or associated with atleast some of the associated devices, systems, assemblies, circuitry,sensors, electrodes, components of the devices and/or managers, engines,parameters, functions etc. described throughout the present disclosure.

For purposes of the present disclosure, in reference to the controller302, with embodiments in which the electronics assembly 306 comprises orincludes at least one processor, the term “processor” shall mean apresently developed or future developed processor (or processingresources) or microprocessor that executes sequences of machine readableinstructions contained in a memory. In some examples, execution of thesequences of machine readable instructions, such as those provided viathe memory 304 of the control portion 300 cause the processor to performactions, such as operating the controller 302 to implement sleepdisordered breathing (SDS) therapy and related management and/ormanagement and operation of designated physical action sensing, asgenerally described in (or consistent with) at least some examples ofthe present disclosure. The machine readable instructions may be loadedin a random access memory (RAM) for execution by the processor fromtheir stored location in a read only memory (ROM), a mass storagedevice, or some other persistent storage (e.g., non-transitory tangiblemedium or non-volatile tangible medium, as represented by the memory304. In some examples, the memory 304 comprises a computer readabletangible medium providing non-volatile storage of the machine readableinstructions executable by a process of the controller 302. In otherexamples, hard wired circuitry may be used in place of or in combinationwith machine readable instructions to implement the functions described.For example, the electronics assembly 306 may be embodied as part of atleast one application-specific integrated circuit (ASIC), at least oneintegrated circuit, a microprocessor and ASIC, etc. In at least someexamples, the controller 302 is not limited to any specific combinationof hardware circuitry and machine readable instructions, nor limited toany particular source for the machine readable instructions executed bythe controller 302.

FIG. 9B is a diagram 320 schematically illustrating at least somemanners in which the control portion 300 can be implemented, accordingto one example of the present disclosure. In some examples, the controlportion 300 is entirely implemented within or by an IPG assembly 322,which has at least some of substantially the same features andattributes as the IPG assembly 52 as previously described in associationwith at least FIG. 2 . In some examples, the control portion 300 isentirely implemented within or by a remote control 330 (e.g. aprogrammer) external to the patient's body, such as a patient control332 and/or a physician control 334. In some embodiments, the remotecontrol 330 is akin to the external device 36 (FIG. 1 ) described above.In some examples, the control portion 300 is partially implemented inthe IPG assembly 322 and partially implemented in the remote control 330(at least one of the patient control 332 and the physician control 334).In some examples the control portion 300 may be implemented via a serveraccessible via the cloud and/or other network pathways. In someexamples, the control portion 300 may be distributed or apportionedamong multiple devices or resources such as among a server, an IMD,and/or a user interface

In some examples, in association with the control portion 300, the userinterface (310 in FIG. 9C) is implemented in the remote control 330.FIG. 9C is a block diagram schematically representing the user interface310, according to one example of the present disclosure. In someexamples, the user interface 310 forms part or and/or is accessible viaa device external to the patient and by which the therapy system may beat least partially controlled and/or monitored. The external devicehosting the user interface 310 may be a patient remote (e.g., 332 inFIG. 9B, for example a smartphone operating a custom softwareapplication), a physician remote (e.g., 334 in FIG. 9B) and/or aclinician portal. In some examples, the user interface 310 comprises auser interface or other display that provides for the simultaneousdisplay, activation, and/or operation of at least some of the varioussystems, assemblies, circuitry, engines, sensors, components, modules,functions, parameters, as described in association with FIGS. 1-8 . Insome examples, at least some portions or aspects of the user interface310 are provided via a graphical user interface (GUI), and may comprisea display and input.

Returning to FIG. 1 , information from the implantable sensor 32,including the motion-based transducer sensor component, can optionallyutilized to sense or detect other parameters associated with thepatient, that may or may not include involuntary actions. Moreover, insome embodiments, the IMD 30 can be controlled to operate in response toinvoluntary actions by the patient as sensed by the implantable sensor32. Non-limiting examples of some possible control features implementedby the systems and methods of the present disclosure can comprise atleast some of substantially the same features and attributes asdescribed within at least U.S. application Ser. No. 16/092,384, filedOct. 9, 2018 and entitled “ACCELEROMETER-BASED SENSING FOR SLEEPDISORDERED BREATHING (SDB) CARE”, the entire teachings of which areincorporated herein by reference. In related embodiments, the systems ofthe present disclosure can include one or more additional implantablesensors (in addition to the implantable sensor 32). Information signaledby the one or more additional implantable sensors can optionally beemployed (along with information from the implantable sensor 32) as partof the recognition or identification of an occurrence of a posture ofthe patient as described above. Alternatively or in an addition, theinformation signaled by the one or more additional implantable sensorscan be employed in monitoring the patient, formulating a therapyregimen, etc., as described, for example, in U.S. application Ser. No.16/092,384.

Although specific examples have been illustrated and described herein, avariety of alternate and/or equivalent implementations may besubstituted for the specific examples shown and described withoutdeparting from the scope of the present disclosure. This application isintended to cover any adaptations or variations of the specific examplesdiscussed herein.

1. A care system comprising: an implantable sensor configured forimplantation into a patient and to generate information indicative of agravity vector; an implantable medical device (IMD) for deliveringstimulation therapy to the patient; and a monitoring module formonitoring the gravity vector over time.
 2. The care system of claim 1,further comprising: a therapy module for prompting operation of the IMDin delivering stimulation therapy, the therapy module programmed toperform at least one therapy regimen in which stimulation therapy isdelivered to the patient at a predetermined level; wherein the system isprogrammed to, during performance of the at least one therapy regimen:compare the monitored gravity vector with a threshold, and based uponthe comparison, prompt performance of an operational mode in which thestimulation therapy delivered to the patient is ramped down from thepredetermined level to a ramped down level.
 3. The care system of claim2, wherein the system is programmed to prompt performance of theoperational mode once the monitored gravity vector has maintained adesignated relationship with respect to the threshold for apredetermined period of time.
 4. The care system of claim 2, wherein thesystem is programmed to prompt performance of the operational modebased, at least in part, upon a change in the monitored gravity vectorthat exceeds a threshold magnitude.
 5. The care system of claim 2,wherein the system is programmed to prompt performance of theoperational mode based, at least in part, upon the monitored gravityvector falling within a predetermined range.
 6. The care system of claim2, wherein the ramped down level is a pause in delivery of anystimulation therapy.
 7. The care system of claim 2, wherein theoperational mode further includes the stimulation therapy delivered tothe patient being ramped up from the ramped down level to thepredetermined level based, at least in part, upon a comparison of themonitored gravity vector with a predetermined range.
 8. The care systemof claim 7, wherein the system is programmed to initiate ramping up ofthe stimulation therapy delivered to the patient from the ramped downlevel to the predetermined level once the monitored gravity vector hasremained within the predetermined range for a predetermined period oftime.
 9. The care system of claim 2, wherein the system is programmed toautomatically initiate the operational mode without referencing adetermined posture of the patient.
 10. The care system of claim 2,wherein the system is programmed to automatically initiate theoperational mode based solely on the monitored gravity vector.
 11. Thecare system of claim 2, wherein the system is programmed to promptperformance of the operational mode further based upon detected motionof the patient.
 12. The care system of claim 1, further comprising: atherapy module for prompting operation of the IMD in deliveringstimulation therapy, the therapy module programmed to perform at leastone therapy regimen in which stimulation therapy is delivered to thepatient at a predetermined level; wherein the system is programmed to:compare the monitored gravity vector with a threshold, and based uponthe comparison, prompt performance of the at least one therapy regimen.13. The care system of claim 12, wherein the system is programmed toprompt performance of the at least one therapy regimen once themonitored gravity vector has maintained a designated relationship withrespect to the threshold for a predetermined period of time.
 14. Thecare system of claim 12, wherein the prompted performance of the atleast one therapy regimen includes ramping the stimulation therapydelivered to the patient from zero stimulation to the predeterminedlevel.
 15. The care system of claim 12, wherein the system is programmedto prompt performance of the at least one therapy regimen further basedupon detected motion of the patient.
 16. The care system of claim 15,wherein the system is programmed to prompt performance of the at leastone therapy regimen based upon the detected motion of the patientindicating no or minimal movements over a defined time period.
 17. Thecare system of claim 1, wherein the system is programmed to assign atleast one gravity vector orientation relative to the implantable sensorwith at least one operational mode.
 18. The care system of claim 1,wherein the system is programmed to activate delivery of therapy duringa defined time period when no or minimal motion by the patient isdetected and the monitored gravity vector is within a predeterminedrange.
 19. The care system of claim 1, wherein the system is programmedto make changes in a stimulation therapy delivered to the patient basedon repeating changes in the monitored gravity vector.
 20. The caresystem of claim 1, wherein the system is programmed to not determine acurrent posture of the patient.